1. Field of the Invention
The present invention relates to dishwashers. In one aspect, the invention relates to a dishwasher having a zone wash manifold with rotating sprayers. In another aspect, the invention relates to a dishwasher having an enhanced spray pattern for optimizing the cleaning effectiveness of the dishwasher. In yet another aspect, the invention relates to a dishwasher having an improved cooking utensil cleaning capability.
2. Background
Modem dishwashers include a tub and an upper and lower rack or basket for supporting soiled dishes within the tub. A pump is provided for re-circulating wash liquid throughout the tub to remove soils from the dishes. Typically, larger dishes such as casserole dishes which have a propensity to be heavily soiled are carried on the lower rack and lighter soiled dishes such as cups and glasses are provided on an upper rack. The racks are generally configured to be moveable in or out of the tub for loading and unloading.
One of problems associated with the typical modern dishwasher is that the dishes receive somewhat uniform wash treatment no matter their positioning within a rack in the dishwasher. For example, in a typical dishwasher, a lower wash arm rotates about a vertical axis and is provided beneath the lower rack for cleaning the dishes on the lower rack and an upper wash arm is provided beneath the upper rack for cleaning the dishes on the upper rack. Dishes in the upper rack receive somewhat uniform wash treatment and dishes in the lower rack receive somewhat uniform wash treatment. Accordingly, lightly soiled dishes in either dish rack are subject to the same wash performance as the highly soiled dishes in the same wash rack, which can lead to poor wash performance of the highly soiled dishes. As a result, it would be advantageous to provide a dishwasher with a second or concentrated wash zone for washing larger dishes such as the casserole dishes, which are more likely to be heavily soiled.
Another problem associated with the modem dishwasher is that to achieve optimal wash performance of heavily soiled, larger dishes, the dishes may need to be loaded with the surface that needs to be washed face down. The face down approach allows the lower spray arm to reach the heavily soiled surface. Accordingly, it would be advantageous if the dishwasher could be provided with a second wash zone that allowed the heavily soiled dishes to be loaded in an upright position, thereby optimizing the number of dishes that can be loaded in the dishwasher on any given cycle. It would also be advantageous if the dishwasher allowed for a customized wash cycle option which optimized the use of the second wash zone.
A stationary zone wash spray manifold in combination with a rotating spray arm assembly is highly effective in washing heavily soiled dishes which are loaded in an upright position. However, the combination of spray from a conventional rotating spray arm assembly and a zone wash spray manifold contributes to high water usage. While the cleaning of the heavily soiled dishes may be optimized with this assembly, the high volume of wash liquid required results in less volume delivered to other spray assemblies and potentially less effective cleaning of other dishes. The stationary manifold also limits the size of the wash zone, thereby limiting the effectiveness of the cleaning operation.